Alkylbenzenes are useful, for example, as intermediates in the production of various end products. It is known that alkali metals, when reacted with alkylbenzenes, will displace benzylic hydrogens. The resulting alkylbenzene anion/alkali metal cation pair will undergo a reaction with olefins at certain temperatures to give alkylation products in which some or all saturated benzylic carbon atoms are alkylated in such a way as to replace some or all of the benzylic hydrogen atoms on a carbon atom with one aliphatic chain per benzylic hydrogen atom. Such reactions can yield a variety of products, depending on the number of saturated benzylic carbon atoms and the number of hydrogen atoms on a given benzylic carbon atom. In the commercial production of alkylbenzenes, a product of high purity is generally desired, and byproducts must be removed. Several patents and publications address issues related to providing suitable methods for commercial production of alkylbenzenes. See, e.g., U.S. Pat. No. 4,950,831 and U.S. Pat. No. 6,100,437.
A particular alkylbenzene, propylbenzene, can be used, e.g., in textile dyeing and printing, as a solvent for cellulose acetate in the manufacture of methylstyrene, and in various consumer products.
Various methods for production of propylbenzene are published in the literature. For example, publications indicate that propylbenzene can be made by alkylation of benzene with cyclopropane, by isomerization of cumene using zeolite, by Friedel-Crafts acylation of benzene with propionyl chloride, or by reaction of toluene and ethylene using NaK.
In spite of these publications, and efforts by others to improve the production of alkylbenzenes, to our knowledge propylbenzene is not widely produced commercially in significant quantities. Thus, economically-efficient methods that provide propylbenzene products of commercially suitable purity are needed.